1. Field of the Invention
The present invention relates to an ion sensing device, and more particularly, to a hydrogen ion sensing device using an arrayed gated lateral bipolar junction transistor of a MOS hybrid mode having highly-improved ion sensitivity.
2. Description of the Related Art
Hydrogen ions have various kinds of electrolytes which are required for the industrial world as well as the livelihood of the organisms and have their respective constant ranges of concentrations during support of life. pH is a factor critical in understanding a chemical reaction and a chemical property of substance. In particular, pH is a parameter critical in determining a property of a solution containing a target of measurement. A pH sensor is required to make a quantitative measurement of pH.
Such a pH measurement is the first step in determining a chemical property of substance as well as controlling a chemical reaction. The pH measurement is currently in wide use for many applications including the water-related industries, chemical industries, public health, agriculture, fishing industries, biology-related industries, etc.
As examples of sensors used to measure pH (power of hydrogen) which is a logarithm of hydrogen ion concentration, ISE (Ion Selective Electrode), ISFET (Ion Selective Field Effect Transistor), LAPS (Light Addressable Potentiometric Sensor) and so on are mainly being studied.
In recent years, a new concept of semiconductor devices used to make a measurement of hydrogen ion concentration has been reported. Representative examples may include semiconductor devices employing a charge transfer technique and a GaAs AlGaN/GaN HEMT technique. These studies are different from typical studies to improve sensitivity using new sensing materials based on an intrinsic FET theory or improve stability by adding particular peripheral circuits.
Such recent studies show results beyond the limit of physical sensitivity and Nernst sensitivity of sensing portions. As an extension of these studies, there is a need for development of devices exhibiting new electrical characteristics using established silicon-based MOS technologies for exploitation of new applications, and development of new electronic devices implementing high sensitivities.